Seat belt webbing double faced with ribs

ABSTRACT

A webbing for seat belts having a plurality of warp yarns interwoven with a plurality of weft yarns which are inserted through a shed in the warp yarns is provided. The warp yarns include a first group and a second group, with the second group of warp yarns having a higher density across a portion of the width of the shed than the warp yarns of the first group. At least some of the warp yarns in the second group are separated from one another by the warp yarns of the first group. The webbing has two faces and is flexible from a first, generally flat position to a second, flexed position. When the webbing is in the generally flat position, the first and second groups of warp yarns on one fabric face define a generally smooth surface. When the webbing is in the second, flexed position in which a first portion of the one fabric face is separated from a second portion of the one fabric face by a transition area, and the first portion is positioned generally at an angle α of less than 180° from the second portion of the one fabric face, at least a portion of the second group of warp yarns in the transition area protrude at least partially from the generally smooth surface to define a plurality of ribs.

BACKGROUND OF THE INVENTION

Briefly stated, the present invention relates to seat belt webbing, andmore particularly to an improved seat belt webbing having lowlongitudinal stiffness and reduced friction characteristics to assist inretraction and extraction of the seat belt.

Seat belt (also called safety belt) systems have evolved significantlyas these systems have become standard equipment in all types ofautomotive vehicles. Different designs of seat belts have been providedfor various types of systems, depending upon the properties desired. Ithas been recognized that in order to provide an effective seat beltsystem, it is preferable that the seat belt webbing have variousdesirable characteristics.

Desirable characteristics of seat belt webbing typically include: goodlateral stiffness to help prevent roping or twisting of the seat belt,such as within the “D” ring upon extraction or retraction which couldlead to a malfunction of the seat belt system; low longitudinalstiffness to reduce the retraction and extraction of the seat belt intoand out of the seat belt winding mechanism; good abrasion resistance tohelp ensure a long product life; and passenger comfort to promoteproduct use.

Passenger comfort is often associated with reduced spring tension in thewinding mechanism. The winding mechanism is used to retract the seatbelt when not in use, and typically include a spool upon which thewebbing is coiled as well as a spring for applying tension to the seatbelt as it is extracted so that it can be automatically retracted whenreleased by the user. The spring tension must be high enough so that theseat belt webbing will be fully retracted with reliability, but thespring tension must not be so great that it causes discomfort to theuser as the seat belt is being fastened and worn. A main force resistingretraction of the seat belt webbing is friction generated between thesurface of the seat belt webbing and the guide members of the seat beltrestraint system through which it passes. All of these traits are nowbeing considered more by purchasers of automobiles when evaluatingoverall automobile quality, and accordingly, are being carefullyevaluated by manufacturers for improvement.

It would be desirable to provide a woven seat belt webbing having all ofthe desired characteristics as set forth above, as well as a seat beltwebbing which permits a winding mechanism with reduced spring tension tobe used in order to increase user comfort.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present invention is a webbing for seat belts havinga plurality of warp yarns interwoven with a plurality of weft yarnswhich are inserted through a shed in the warp yarns. The warp yarnsinclude a first group and a second group, with the second group of warpyarns having a higher density across a portion of the width of the shedthan the warp yarns of the first group. At least some of the warp yarnsin the second group are separated from one another by the warp yarns ofthe first group. The webbing has two faces and is flexible from a first,generally flat position to a second, flexed position. When the webbingis in the generally flat position, the first and second groups of warpyarns on one fabric face define a generally smooth surface. When thewebbing is in the second, flexed position, in which a first portion ofthe one fabric face is separated from a second portion of the one fabricface by a transition area, and the first portion is positioned generallyat an angle α of less than 180° from the second portion of the onefabric face, at least a portion of the second group of warp yarns in thetransition area protrude at least partially from the generally smoothsurface to define a plurality of ribs.

In another aspect, the present invention provides a webbing for seatbelts having a plurality of warp yarns interwoven with a plurality ofweft yarns. First and second groups of warp yarns are provided. Thefirst group of warp yarns is interwoven with the weft yarns in a firstweave pattern and the second group of warp yarns is interwoven with theweft yarns in a second weave pattern. At least some of the warp yarns inthe second group are separated from one another by the warp yarns fromthe first group. The webbing has two faces and is flexible from a first,generally flat position to a second, flexed position. When the webbingis in the generally flat position, the first and second group of warpyarns on one fabric face define a generally smooth surface. When thewebbing is in the second, flexed position, in which a first portion ofthe one fabric face is separated from a second portion of the one fabricface by a transition area, and the first portion is positioned generallyat an angle α of less than 180° from the second portion of the onefabric face, at least a portion of the second group of warp yarns in thetransition area protrude at least partially from the generally smoothsurface to define a plurality of ribs.

In another aspect, the present invention provides a seat belt system formotor vehicles comprising a seat belt webbing having a plurality of warpyarns interwoven with a plurality of weft yarns which are insertedthrough a shed in the warp yarns. First and second groups of warp yarnsare provided. The second group of warp yarns having a higher densityacross a portion of the width of the shed than the warp yarns of thefirst group. At least some of the warp yarns in the second group areseparated from one another by the warp yarns from the first group. Awinding mechanism having a spool is provided and the seat belt webbingis at least partially coiled on the spool. A shoulder harness guidemember is provided at a position generally corresponding to a user'sshoulder, and a portion of the seat belt webbing passes over theshoulder harness guide member to redirect the seat belt webbing whichextends from the winding mechanism. A buckle member is connected to theseat belt webbing. The seat belt webbing has two faces and is flexiblefrom a first, generally flat position to a second, flexed position. Whenthe webbing is in the generally flat position, the first and secondgroups of warp yarns on one fabric face define a generally smoothsurface. When the webbing is in the second, flexed position, in which afirst portion of the one fabric face is separated from a second portionof the one fabric face by a transition area located at the shoulderharness guide member, and the first portion is positioned at an angle αof less than 180° from the second portion of the one fabric face, atleast a portion of the second group of warp yarns in the transition areaprotrude at least partially from the generally smooth surface to definea plurality of ribs which contact the shoulder harness guide member toreduce friction.

In another aspect, the present invention provides a method of making aseat belt webbing. The method includes:

(a) providing warp yarns in a shedding arrangement for producing a shed;

(b) varying the density of the warp yarns across a width of the shed, toprovide first and second groups of warp yarns, the first group of thewarp yarns having a first density in a direction of the width of theshed and the second group of the warp yarns having a second, higherdensity in the direction of the width of the shed and, at least some ofthe warp yarns of the second group being separated by the warp yarns ofthe first group;

(c) weaving weft yarns with the warp yarns across the width of the shed;

(d ) stitching along one edge of the webbing to hold the weft yarns inplace along the one edge; and

(e) forming elevatable ribs which extend longitudinally along thewebbing from the second group of warp yarns which elevate from an innersurface of the webbing as the webbing is folded in a lateral direction.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofpreferred embodiments of the invention, will be better understood whenread in conjunction with the appended drawings. For the purpose ofillustrating the invention, there is shown in the drawings embodimentswhich are presently preferred. It should be understood, however, thatthe invention is not limited to the precise arrangements andinstrumentalities shown. In the drawings:

FIG. 1 is a schematic illustration of a top plan view of an exemplaryseat belt webbing in accordance with the present invention;

FIG. 2 is a partial weaving chart illustrating a full repeat of awebbing pattern for a preferred embodiment of the seat beat webbing inaccordance with the present invention;

FIG. 3 is an elevational view of a seat belt system using the seat beltwebbing in accordance with the present invention; and

FIG. 4 is a greatly enlarged partial cross-sectional view taken alonglines 4—4 in FIG. 3 showing a cross-section of the webbing in atransition area with the ribs being partially extended from the fabricsurface.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right,” “left,” “lower” and “upper”designate directions in the drawings to which reference is made. Thewords “inwardly” and “outwardly” refer to directions toward and awayfrom, respectively, the geometric center of the seat belt webbing 10 inaccordance with the present invention and designated parts thereof. Theterminology includes the words specifically mentioned above, derivativesthereof and words of similar import.

Referring now to FIG. 1, a schematic illustration of a seat belt webbing10 in accordance with the present invention is shown as it is beingwoven in a needle loom. The seat belt webbing 10 includes a plurality ofwarp yarns 11 which are interwoven with a plurality of weft or fillingyarns 12 which are inserted through a shed in the warp yarns 11. Whilethe weft yarns 12 may in fact be a single continuous strand, as usedherein and as understood by those of ordinary skill in the art, the term“weft yarn” refers to each pass of the weft yarn across the shed. Theseat belt webbing 10 is preferably woven on a conventional needle loom(not shown) which includes a filling insertion arm 13. However, it willbe recognized by those skilled in the art from the present disclosurethat other types of looms may be utilized, if desired.

In the preferred embodiment of the present invention, the webbing 10 iswoven on a needle loom, and it is desirable to provide a knitted edgeformation 43 along one edge of the webbing 10. The edge formation 43provides for an effective and efficient production of the webbing 10,and the edge knitting 43 according to the invention is practiced byknitting either one or more catch cord yarns 44 and/or lock stitch yarnsat the edge portion. The tension is controlled on the locking yarns toensure a uniform edge, such as a Mueller System 3 or a System 5 edge.However, it will be recognized by those skilled in the art from thepresent disclosure, that depending upon the type of loom utilized, alocking yarn 44 may not be required along one edge of the webbing 10 tohold weft yarns 12 in place.

In a preferred embodiment of the webbing 10, the warp yarns 11 have adensity which varies across a width of the shed which correspondsgenerally to the width of the webbing 10. Specifically, the warp yarns11 are divided into a first group 21 and a second group 31, with thesecond group 31 of warp yarns 11 having a higher density across theirportion of the width of the shed than the warp yarns 11 of the firstgroup 21. This can be accomplished by various means.

In a preferred embodiment of the invention illustrated by the weavechart in FIG. 2, the warp yarns 11 of the first group 21 are woven withthe weft yarn 12 in a first weave pattern and the warp yarns 11 of thesecond group 31 are woven with the weft yarns 12 in a second weavepattern. The weave chart in FIG. 2 represents an edge portion 24 on oneside of the webbing 10 and a full repeat 26 which is preferably repeatedacross the width of the webbing 10 until the opposite edge portion (notshown) is reached. The opposite edge portion is preferably a mirrorimage of the edge portion 24. As shown in FIG. 2, at least some of thewarp yarns 11 in the second group 31 are separated from one another bythe warp yarns 11 from the first group 21. In the preferred embodiment,as illustrated in FIG. 2, the first group of warp yarns 21 are wovenwith the weft yarns 12 in a four harness twill, with two weft yarnsbeing provided in each shed due to the use of a needle loom.

As shown in detail in FIG. 2, in one preferred embodiment, the secondgroup 31 of the warp yarns 11 is divided into a number of equally spacedgroupings 32, which are spaced apart by groupings 22 of the warp yarns11 from the first group 21. Preferably there are at least three equallyspaced groupings 32 of warp yarns 11 from the second group, and in thepreferred embodiment, there are eleven equally spaced groupings 32.However, it will be recognized by those skilled in the art from thepresent disclosure that any number of groupings 32 of warp yarns 11 fromthe second group 31 may be provided, and the spacing between thegroupings 32 may be equal or unequal, depending on the particularrequirements of a given application. The groupings 32 of the warp yarns11 from the second group 31 are used to provide ribs 40, as will bedescribed in more detail below in order to provide a seat belt webbing10 with reduced friction characteristics.

The density of the warp yarns 11 can also be varied by increasing thedenier of the warp yarns 11 of the second group 31 relative to the warpyarns 11 of the first group 21. Alternatively, the warp yarns 11 of thesecond group 31 can be woven in pairs, as shown in FIG. 2, or in evengreater numbers, by inserting multiple yarns through a single heddle eyein order to increase the density, while the warp yarns 11 in the firstgroup 21 are preferably woven individually. Additionally, the number ofharnesses, the placement of the heddles in each harness, and/or theharness motion can be varied to vary the density of the warp yarns 11across the width of the shed.

As shown in FIGS. 1 and 2, preferably each grouping 32 of the secondgroup 31 includes at least a single warp yarn 11. More preferably, asshown in FIG. 2, each grouping 32 of warp yarns 11 of the second group31 includes a pair of adjacent warp yarns 11 which have the same weavein order to provide an increased density. Additionally, in the preferredembodiment, each grouping 32 of warp yarns 11 of the second group 31include first and second pairs of adjacent warp yarns, with the firstand second pairs of adjacent warp yarns 11 being woven on opposite sidesof each shed.

As shown in FIG. 1 the weft yarns 12 can be inserted singly, and may beeither monofilament or multi-filament yarns. Furthermore, weft yarns 12may also be inserted in pairs, with one weft yarn being a monofilamentand the other being a multi-filament in order to provide increasedlateral stiffness for the webbing 10.

Referring again to FIG. 2 in the preferred embodiment, the twilldirection of the groupings 22 of warp yarns 11 in the first group 21alternates on opposite sides of each grouping 32 of warp yarns 11 in thesecond group 31. However, it will be recognized by those skilled in theart from the present disclosure that any desired weave pattern can beutilized for the warp yarns 11 of the first group 21, such as a 2×2twill, or any other weave suitable for automotive seat belt webbing.

As shown in FIG. 3, the webbing 10 has two faces 14, 15 and is flexiblefrom a first generally flat position to a second, flexed position. Whenthe webbing is in the generally flat position, the first and secondgroups 21, 31 of warp yarns 11 define a generally smooth surface. Whenthe webbing is in the second, flexed position, in which a first portion17 of the one fabric face 14 is separated from a second portion 18 ofthe one fabric face 14 by a transition area 19, and the first portion 17is positioned generally at an angle α of less than 180° from the secondportion 18 of the first fabric face 14, at least a portion of the secondgroup 31 of warp yarns in the transition area 19 protrude at leastpartially from the generally smooth surface to define a plurality ofribs 40, as shown in FIG. 4. Preferably, there are at least threeequally spaced ribs 40. The ribs 40 are spaced apart at a predetermineddistance, which is preferably based upon at least the lateral stiffnessof the webbing 10, and preferably the lateral and longitudinalstiffness, such that at least some of the interwoven warp yarns 11 ofthe first group 21 which are located between adjacent ribs 40 arebridged over a guide member 42 which contacts the ribs 40 protrudingfrom the one face 14 of the webbing 10 in the transition area 19 toreduce friction as the webbing 10 slides over the guide member 42.

In the preferred embodiment, based upon the weave pattern, each rib 40appears to be continuous in nature due to the adjacent pairs of warpyarns 11 of each grouping 32 being woven on opposite sides of each shed,such that as the webbing 10 is woven, the first and second adjacentpairs of warp yarns 11 in each grouping 32 are forced together and forma nearly continuous rib 40. However, it will be recognized by thoseskilled in the art from the present disclosure that the ribs 40 may bediscontinuous, as illustrated schematically in FIG. 1, and that adjacentribs 40 may have oppositely spaced weave patterns such that, while eachrib 40 is discontinuous, preferably at least a portion of one of theribs 40 in adjacent pairs of ribs 40 contacts the guide member 42 in thetransition area 19 at any given time.

It will recognized by those skilled in the art that the presentinvention is not limited to any particular weave pattern or anyparticular types of warp or weft yarns 11, 12. The warp and weft yarns11, 12 may be either single or multiple ply yarns of any given denier,and may be twisted or untwisted. The deniers of the warp and weft yarns11, 12 are preferably chosen depending upon the type of yarn used and aparticular customer's requirement. Additionally, different types of weftyarns or warp yarns may be used within a single webbing in order toobtain different properties from different yarns. For example, when theweft yarns 12 are inserted in pairs, one yarn may have differentproperties than the other yarn. It will be similarly recognized that theheight, density and thickness of the ribs 40 as well as the locationsselected for the ribs 40 may also be varied depending upon a particularcustomer's requirements and the ribs 40 may be spaced uniformly ornon-uniformly, as desired.

Preferably, the warp yarns 11 are single ply polyester yarns having adenier of about 1300. The weft yarn 12 is preferably a multi-filamentyarn comprised of polyester and having a denier of about 840. The catchcord 44 is preferably a polyester yarn having an denier of about 500.The webbing 10 preferably is provided with a good lateral stiffness, lowlongitudinal stiffness, abrasion resistance and enhanced user comfortdue to the ribs 40 which protrude in the transition area 19 as thewebbing 10 passes over a guide member 42 in a seat belt system. In thepreferred embodiment, the webbing 10 is approximately two inches wide.However, the webbing 10 can be used in applications in which the widthis preferably between 1.0 and 4.0 inches. It is also possible to makethe webbing 10 in other narrower or wider sizes for various otherapplications. It is also possible to make the webbing with additionalfeatures including, but not limited to, standard and high elongations,and various round and other comfort edges.

Referring again to FIG. 3, a seat belt system 48 is shown in detail andincludes the seat belt webbing 10 which is provided on a windingmechanism 50 having a spool 52, with the seat belt webbing 10 being atleast partially coiled on the spool 52. The shoulder harness guidemember 42 is provided at a position generally corresponding to a user'sshoulder, and the seat belt webbing 10 passes over the shoulder harnessguide member 42 to redirect the seat belt webbing 10 which extends fromthe winding mechanism 52. A buckle member 54 is connected to the seatbelt webbing 10 by passing through an opening in the buckle member 54,and the end of the seat belt webbing is anchored in a fixed position(not shown). However, it will be recognized by those skilled in the artfrom the present disclosure that the seat belt webbing 10 may be used inother types of retractable seat belt systems. As the seat belt webbing10 is drawn across the guide member 42, the groupings 32 of warp yarns11 in the second group 31 protrude from the generally smooth surface onthe face 14 of the seat belt webbing 10 facing the guide member 42 toreduce friction.

The webbing 10 is made by providing warp yarns 11 in a shed with thedensity of the warp yarns 11 being varied across the width of the shed.The first group 21 of the warp yarns 11 has a first density in adirection of the width of the shed and the second group 31 of warp yarns11 have a second, higher density in the direction of the width of theshed, and at least some of the warp yarns 11 of the second group 31 areseparated by warp yarns 11 of the first group 21. Weft yarns 12 arewoven with the warp yarns 11 across the width of the shed and arepreferably stitched along one edge of the webbing using a catch cord 44.Elevatable ribs 40 which are located longitudinally along the webbing 10are formed from the second group 31 of warp yarns 11 which elevate froman inside surface 14 of the webbing 10 as the webbing 10 is folded in alongitudinal direction to produce a lateral fold.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

What is claimed is:
 1. A shed for seat belts comprising: a plurality ofwarp yarns interwoven with a plurality of weft yarns which are insertedthrough a shed in the warp yarns, the warp yarns including a first groupand a second group, the second group of the warp yarns having a higherdensity across a portion of a width of the shed than the warp yarns ofthe first group, at least some of the warp yarns in the second groupbeing separated from one another by the warp yarns from the first group;the webbing having two faces and being flexible from a first, generallyflat position, in which the first and second groups of warp yarns on onefabric face define a generally smooth surface, to a second, flexedposition, in which a first portion of the one fabric face is separatedfrom a second portion of the one fabric face by a transition area, thefirst portion being positioned generally at an angle α of less than 180°from the second portion of the one fabric face, such that at least aportion of the second group of warp yarns in the transition areaprotrude at least partially from the generally smooth surface to definea plurality of ribs.
 2. The webbing for seat belts of claim 1 whereinthe second group of the warp yarns is divided into a plurality ofgroupings.
 3. The webbing for seat belts of claim 2 wherein thegroupings of the second group of the warp yarns are equally spaced. 4.The webbing for seat belts of claim 2 wherein each of the groupings ofthe second group includes first and second pairs of adjacent warp yarns,the first and second pairs of adjacent warp yarns are woven on oppositesides for each shed.
 5. The webbing for seat belts of claim 2 whereineach grouping of second group includes a pair of adjacent warp yarnswhich have the same weave.
 6. The webbing for seat belts of claim 2wherein each grouping of second group includes a single warp yarn. 7.The webbing for seat belts of claim 1 wherein the weft yarns areinserted in pairs.
 8. The webbing for seat belts of claim 1 wherein thewarp yarns of the first group are woven with the weft yarns in a firstweave pattern and the warp yarns of the second group are woven with theweft yarns in a second weave pattern.
 9. The webbing for seat belts ofclaim 8, wherein the first group of the warp yarns are woven in a fourharness twill.
 10. The webbing for seat belts of claim 9 wherein thetwill direction alternates between groupings of the warp yarns in thefirst group of warp yarns which are separated by groupings of the warpyarns in the second group of warp yarns.
 11. The webbing for seat beltsof claim 1 wherein the webbing is between 1.0 and 4.0 inches wide. 12.The webbing for seat belts of claim 1 wherein there are at least threeequally spaced ribs.
 13. The webbing for seat belts of claim 1 whereinthe ribs are spaced apart at a predetermined distance based on at leasta lateral stiffness of the webbing such that at least some of theinterwoven warp yarns of the first group which are located betweenadjacent ribs are adapted to be bridged over a guide member whichcontacts the ribs protruding from the one face of the webbing in thetransition area to reduce friction as the webbing slides over the guidemember.
 14. The webbing for seat belts of claim 1 wherein each rib isdiscontinuous.
 15. The webbing for seat belts of claim 1 wherein thesecond group of warp yarns has a different denier than the first groupof warp yarns.
 16. The webbing for seat belts of claim 1 wherein thewarp yarns and the weft yarns are at least one of multi-filament yarns,monofilament yarns, and a combination of multifilament and monofilamentyarns.
 17. The webbing for seat belts of claim 1 wherein the warp yarnsin the first group are woven individually and the warp yarns of thesecond group are woven in pairs.
 18. A webbing for seat beltscomprising: a plurality of warp yarns interwoven with a plurality ofweft yarns, the warp yarns including a first group of warp yarns and asecond group of warp yarns, the first group of warp yarns beinginterwoven with the weft yarns in a first weave pattern and the secondgroup of warp yarns being interwoven with the weft yarns in a secondweave pattern, at least some of the warp yarns in the second group beingseparated from one another by the warp yarns from the first group; thewebbing having two faces and being flexible from a first, generally flatposition, in which the first and second groups of warp yarns on onefabric face define a generally smooth surface, to a second, flexedposition in which a first portion of the one fabric face is separatedfrom a second portion of the one fabric face by a transition area, thefirst portion being positioned generally at an angle α of less than 180°from the second portion of the one fabric face, such that at least aportion of the second group of warp yarns in the transition areaprotrude at least partially from the generally smooth surface to definea plurality of ribs.
 19. The webbing for seat belts of claim 18 whereinthe warp yarns are spaced such that a warp yarn density across thefabric width varies, with the second group of warp yarns has anincreased density in comparison to the first group of warp yarns.
 20. Amethod of making a seat belt webbing, comprising: (a) providing warpyarns in a shed, (b) varying the density of the warp yarns across awidth of the shed, a first group of the warp yarns having a firstdensity in a direction of the width of the shed and a second group ofthe warp yarns having a second, higher density in the direction of thewidth of the shed, at least some of the warp yarns of the second groupbeing separated by warp yarns of the first group; (c) weaving weft yarnswith the warp yarns across the width of the shed; (d) stitching alongone edge of the webbing to hold the weft yarns in place along the oneedge; (e) forming elavatable ribs which extend longitudinally along thewebbing from the second group of warp yarns which elevate from an innersurface of the webbing as the webbing is folded in a longitudinaldirection to produce a lateral fold.